diff --git a/package-lock.json b/package-lock.json
index 70bb59c..59906c4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -13,6 +13,7 @@
         "@prisma/client": "5.6.0",
         "@radix-ui/react-checkbox": "^1.0.4",
         "@radix-ui/react-dropdown-menu": "^2.0.6",
+        "@radix-ui/react-hover-card": "^1.0.7",
         "@radix-ui/react-icons": "^1.3.0",
         "@radix-ui/react-label": "^2.0.2",
         "@radix-ui/react-popover": "^1.0.7",
@@ -755,6 +756,37 @@
         }
       }
     },
+    "node_modules/@radix-ui/react-hover-card": {
+      "version": "1.0.7",
+      "resolved": "https://registry.npmjs.org/@radix-ui/react-hover-card/-/react-hover-card-1.0.7.tgz",
+      "integrity": "sha512-OcUN2FU0YpmajD/qkph3XzMcK/NmSk9hGWnjV68p6QiZMgILugusgQwnLSDs3oFSJYGKf3Y49zgFedhGh04k9A==",
+      "dependencies": {
+        "@babel/runtime": "^7.13.10",
+        "@radix-ui/primitive": "1.0.1",
+        "@radix-ui/react-compose-refs": "1.0.1",
+        "@radix-ui/react-context": "1.0.1",
+        "@radix-ui/react-dismissable-layer": "1.0.5",
+        "@radix-ui/react-popper": "1.1.3",
+        "@radix-ui/react-portal": "1.0.4",
+        "@radix-ui/react-presence": "1.0.1",
+        "@radix-ui/react-primitive": "1.0.3",
+        "@radix-ui/react-use-controllable-state": "1.0.1"
+      },
+      "peerDependencies": {
+        "@types/react": "*",
+        "@types/react-dom": "*",
+        "react": "^16.8 || ^17.0 || ^18.0",
+        "react-dom": "^16.8 || ^17.0 || ^18.0"
+      },
+      "peerDependenciesMeta": {
+        "@types/react": {
+          "optional": true
+        },
+        "@types/react-dom": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/@radix-ui/react-icons": {
       "version": "1.3.0",
       "resolved": "https://registry.npmjs.org/@radix-ui/react-icons/-/react-icons-1.3.0.tgz",
diff --git a/package.json b/package.json
index 409aa0c..d488774 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
     "@prisma/client": "5.6.0",
     "@radix-ui/react-checkbox": "^1.0.4",
     "@radix-ui/react-dropdown-menu": "^2.0.6",
+    "@radix-ui/react-hover-card": "^1.0.7",
     "@radix-ui/react-icons": "^1.3.0",
     "@radix-ui/react-label": "^2.0.2",
     "@radix-ui/react-popover": "^1.0.7",
diff --git a/src/app/groups/[groupId]/edit/page.tsx b/src/app/groups/[groupId]/edit/page.tsx
index 1fcf225..be1a5a8 100644
--- a/src/app/groups/[groupId]/edit/page.tsx
+++ b/src/app/groups/[groupId]/edit/page.tsx
@@ -1,5 +1,5 @@
 import { GroupForm } from '@/components/group-form'
-import { getGroup, updateGroup } from '@/lib/api'
+import { getGroup, getGroupExpensesParticipants, updateGroup } from '@/lib/api'
 import { groupFormSchema } from '@/lib/schemas'
 import { Metadata } from 'next'
 import { notFound, redirect } from 'next/navigation'
@@ -23,5 +23,12 @@ export default async function EditGroupPage({
     redirect(`/groups/${group.id}`)
   }
 
-  return <GroupForm group={group} onSubmit={updateGroupAction} />
+  const protectedParticipantIds = await getGroupExpensesParticipants(groupId)
+  return (
+    <GroupForm
+      group={group}
+      onSubmit={updateGroupAction}
+      protectedParticipantIds={protectedParticipantIds}
+    />
+  )
 }
diff --git a/src/components/group-form.tsx b/src/components/group-form.tsx
index d2140f0..7bf0f8e 100644
--- a/src/components/group-form.tsx
+++ b/src/components/group-form.tsx
@@ -18,6 +18,11 @@ import {
   FormLabel,
   FormMessage,
 } from '@/components/ui/form'
+import {
+  HoverCard,
+  HoverCardContent,
+  HoverCardTrigger,
+} from '@/components/ui/hover-card'
 import { Input } from '@/components/ui/input'
 import { getGroup } from '@/lib/api'
 import { GroupFormValues, groupFormSchema } from '@/lib/schemas'
@@ -28,9 +33,14 @@ import { useFieldArray, useForm } from 'react-hook-form'
 export type Props = {
   group?: NonNullable<Awaited<ReturnType<typeof getGroup>>>
   onSubmit: (groupFormValues: GroupFormValues) => Promise<void>
+  protectedParticipantIds?: string[]
 }
 
-export function GroupForm({ group, onSubmit }: Props) {
+export function GroupForm({
+  group,
+  onSubmit,
+  protectedParticipantIds = [],
+}: Props) {
   const form = useForm<GroupFormValues>({
     resolver: zodResolver(groupFormSchema),
     defaultValues: group
@@ -48,6 +58,7 @@ export function GroupForm({ group, onSubmit }: Props) {
   const { fields, append, remove } = useFieldArray({
     control: form.control,
     name: 'participants',
+    keyName: 'key',
   })
 
   return (
@@ -115,7 +126,7 @@ export function GroupForm({ group, onSubmit }: Props) {
             </CardDescription>
           </CardHeader>
           <CardContent>
-            <ul className="flex flex-col gap-4">
+            <ul className="flex flex-col gap-2">
               {fields.map((item, index) => (
                 <li key={item.id}>
                   <FormField
@@ -129,15 +140,39 @@ export function GroupForm({ group, onSubmit }: Props) {
                         <FormControl>
                           <div className="flex gap-2">
                             <Input className="text-base" {...field} />
-                            <Button
-                              variant="ghost"
-                              className="text-destructive"
-                              onClick={() => remove(index)}
-                              type="button"
-                              size="icon"
-                            >
-                              <Trash2 className="w-4 h-4" />
-                            </Button>
+                            {item.id &&
+                            protectedParticipantIds.includes(item.id) ? (
+                              <HoverCard>
+                                <HoverCardTrigger>
+                                  <Button
+                                    variant="ghost"
+                                    className="text-destructive-"
+                                    type="button"
+                                    size="icon"
+                                    disabled
+                                  >
+                                    <Trash2 className="w-4 h-4 text-destructive opacity-50" />
+                                  </Button>
+                                </HoverCardTrigger>
+                                <HoverCardContent
+                                  align="end"
+                                  className="text-sm"
+                                >
+                                  This participant is part of expenses, and can
+                                  not be removed.
+                                </HoverCardContent>
+                              </HoverCard>
+                            ) : (
+                              <Button
+                                variant="ghost"
+                                className="text-destructive"
+                                onClick={() => remove(index)}
+                                type="button"
+                                size="icon"
+                              >
+                                <Trash2 className="w-4 h-4" />
+                              </Button>
+                            )}
                           </div>
                         </FormControl>
                         <FormMessage />
diff --git a/src/components/ui/hover-card.tsx b/src/components/ui/hover-card.tsx
new file mode 100644
index 0000000..e54d91c
--- /dev/null
+++ b/src/components/ui/hover-card.tsx
@@ -0,0 +1,29 @@
+"use client"
+
+import * as React from "react"
+import * as HoverCardPrimitive from "@radix-ui/react-hover-card"
+
+import { cn } from "@/lib/utils"
+
+const HoverCard = HoverCardPrimitive.Root
+
+const HoverCardTrigger = HoverCardPrimitive.Trigger
+
+const HoverCardContent = React.forwardRef<
+  React.ElementRef<typeof HoverCardPrimitive.Content>,
+  React.ComponentPropsWithoutRef<typeof HoverCardPrimitive.Content>
+>(({ className, align = "center", sideOffset = 4, ...props }, ref) => (
+  <HoverCardPrimitive.Content
+    ref={ref}
+    align={align}
+    sideOffset={sideOffset}
+    className={cn(
+      "z-50 w-64 rounded-md border bg-popover p-4 text-popover-foreground shadow-md outline-none data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[side=bottom]:slide-in-from-top-2 data-[side=left]:slide-in-from-right-2 data-[side=right]:slide-in-from-left-2 data-[side=top]:slide-in-from-bottom-2",
+      className
+    )}
+    {...props}
+  />
+))
+HoverCardContent.displayName = HoverCardPrimitive.Content.displayName
+
+export { HoverCard, HoverCardTrigger, HoverCardContent }
diff --git a/src/lib/api.ts b/src/lib/api.ts
index 4ae88ef..2968cae 100644
--- a/src/lib/api.ts
+++ b/src/lib/api.ts
@@ -66,6 +66,18 @@ export async function deleteExpense(expenseId: string) {
   })
 }
 
+export async function getGroupExpensesParticipants(groupId: string) {
+  const expenses = await getGroupExpenses(groupId)
+  return Array.from(
+    new Set(
+      expenses.flatMap((e) => [
+        e.paidById,
+        ...e.paidFor.map((pf) => pf.participantId),
+      ]),
+    ),
+  )
+}
+
 export async function updateExpense(
   groupId: string,
   expenseId: string,